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Biology Module 6 > 21.1 DNA profiling and PCR > Flashcards

21.1 DNA profiling and PCR Flashcards

1
Q

what is the genome?

A

all of the genetic material an organism contains

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2
Q

what is a VNTR?

A

variable number tandem repeats

short sequences of DNA which are repeated many times within introns

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3
Q

what is a STR?

A

SHORTER sequences of DNA which are repeated many times

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4
Q

trend in the differences in repeats

A

different people have a different number of repeats so a different satellite pattern

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5
Q

what does DNA profiling do?

A

allow you to identify an individual and determine familial relationships

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6
Q

when is DNA profiling used?

A

forensics
family genetics
medical diagnosis

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7
Q

forensics

A

used to profile blood to link DNA on a crime scene to the DNA of suspects

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8
Q

medical diagnosis

A

allows you to identify mutations

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9
Q

first step of DNA fragmentation

A

extract the DNA
but not a lot of DNA
therefore PCR is done to replicate DNA to get more copies

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10
Q

second step of DNA fragmentation

A

enzymes are used to cut the DNA at specific sites to create different fragments

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11
Q

what enzymes are used to cut up the DNA sample into fragments?

A

restriction endonuclease

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12
Q

what are the sites at which restriction endonucleases cut at?

A

the restriction site

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13
Q

what happens to the VNTRs after fragmentation?

A

they stay in the same positions in the DNA fragments

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14
Q

what technique is used to separate cut fragments of DNA?

A

electrophoresis

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15
Q

what is gel electropheresis?

A

technique which utilises the way charged particles can move through a gel medium using an electrical current

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16
Q

what gel is used in electrophoresis?

A

agarose

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17
Q

how is the current induced on a gel plate?

A

the wells containing the DNA fragments are found at the negative end

the other side has the positive end

18
Q

what is the gel immersed in to separate the DNA strands?

A

in alkali

19
Q

why does the DNA move up the gel plate?

A

DNA is negatively charged and is therefore repelled by the negatively charged bottom of the plate upwards
AND
attracted by the positively charged top

20
Q

how are the DNA fragments separated in electrophoresis?

A

the smaller fragments move to the positive electrode QUCKER

the larger fragments move to the positive electrode SLOWER

means that larger and smaller fragments are spread out

21
Q

why is alkali added to the gel?

A

to turn the DNA into single strands

22
Q

what type of blotting is done to the DNA strands?

A

southern blotting

23
Q

what is southern blotting?

A

a nylon sheet is used to soak up the data onto a paper

24
Q

what are the 2 types of DNA probes?

A

radioactive
fluorescent

25
Q

how do the DNA probes bind to the DNA?

A

they are complimentary to the base sequence of the DNA

26
Q

what is used in electrophoresis to identify DNA fragments?

A

a DNA ladder

27
Q

how are the results seen using radioactive probes?

A

by using an X-ray

28
Q

how are the results seen using fluorescent probes?

A

UV light is used and the probes glow

29
Q

what is the PCR version of DNA?

A

an artificial replication of DNA from a small sample to produce a large sample

30
Q

what is a PCR machine called?

A

a thermal cycler

31
Q

step 1 in PCR

A

95 degrees

the hydrogen bonds in the DNA fragment are broken by a high temperature which separates DNA into two strands

32
Q

step 2 in PCR

A

55 degrees

the DNA primers anneal to the ends of the separated DNA strands

33
Q

step 3 in PCR

A

72 degrees (optimum for polymerase)

DNA polymerase used to attach complimentary nucleotides starting from the DNA primer

DNA polymerase forms phosphodiester bonds between adjacent nucleotides

34
Q

product of PCR after the first cycle?

A

four strands of DNA

so 2 DNA molecules

35
Q

what DNA polymerase is used for the synthesis of the DNA in PCR?

A

Taq polymerase

36
Q

why is Taq polymerase thermophilic?

A

high temperatures cannot denature Taq polymerase hence it is useful in PCR where temperatures are high

allows PCR to continually happen without needing to replace enzymes

37
Q

what does DNA ligase do?

A

make phosphodiester bonds

38
Q

how is PCR done with RNA fragments?

A

same process as with DNA

39
Q

how is PCR done with proteins?

A

as proteins can be positively and negatively charged, a chemical needs to denature the protein to ensure all the proteins have the same charge

40
Q

what is different about the genomes of different humans?

A

the NON-CODING regions

VNTRs are many repeats of introns which are unique to humans

allows use to compare the genomes of humans

coding regions are much similar between humans

Biology Module 6 (33 decks)

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